Plasma disappearance curves of intravenously injected Cu67 and orally administered Cu64 are defined simultaneously and analyzed by computer in terms of a multicompartmental model of copper metabolism. The computer analysis permits quantitation of various parameters of intestinal copper absorption, hepatic copper uptake, incorporation of copper into ceruloplasmin, copper excretion, and other aspects of internal copper transport. The primary goal of these studies is adequate understanding of normal copper metabolism and the abnormalities of copper metabolism in Wilson's disease and the determination of a set of kinetic criteria for diagnosis of the heterozygous state in Wilson's disease. In addition, similar studies of copper metabolism will be performed in other disorders, such as primary biliary cirrhosis and prolonged cholestasis, which have previously been shown to be associated with increased copper accumulation in the body.